title: Aluminum water treatment residuals as permeable reactive barrier sorbents to reduce phosphorus losses.
abstract: Two aluminum water treatment residuals (Al-WTRs) from water treatment plants in Manatee County, FL and Punta Gorda, FL were evaluated as potential permeable reactive barrier (PRB) media to reduce groundwater phosphorus (P) losses. Short-term (<24h) P sorption kinetics and long-term P sorption capacity were determined using batch equilibration studies. Phosphorus desorption was characterized following P loadings of 10, 20, 30, 40 and >70 g kg(-1). Sorption and desorption studies were conducted on the <2.0mm material and three size fractions within the <2.0mm material. The effect of dissolved organic carbon (DOC) on P retention was determined by reacting Al-WTRs with P-spiked groundwater samples of varying initial DOC concentrations. Phosphorus sorption kinetics were rapid for all size fractions of both Al-WTRs (>98% P sorption effectiveness at shaking times ≥2 h). The effect of DOC was minimal at <150 mg DOCL(-1), but modest reductions (<22%) in P sorption effectiveness occurred at 587 mg DOC L(-1). The P sorption capacities of the Manatee and Punta Gorda Al-WTRs (<2.0mm) are ∼44 g kg(-1) and >75 g kg(-1), respectively, and the lifespan of an Al-WTR PRB is likely many decades. Desorption was minimal (<2% of the P sorbed) for cumulative P loadings <40 g kg(-l), but increased (<9% of the P sorbed) at cumulative P loads >70 g kg(-1). The <2.0mm Manatee and Punta Gorda Al-WTRs are regarded as ideal PRB media for P remediation.
authors.affiliation: Soil and Water Sci. Dep., Univ. Florida, Gainesville, FL 32611-0510, United States.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Miller
authors.forename: Jehangir H
authors.initials: JH
authors.lastname: Bhadha
authors.forename: George A
authors.initials: GA
authors.lastname: O'Connor
authors.forename: James W
authors.initials: JW
authors.lastname: Jawitz
authors.forename: Jennifer
authors.initials: J
authors.lastname: Mitchell
mesh_terms: D000042:Absorption; D000327:Adsorption; D000535:Aluminum / Q000032:analysis* / Q000737:chemistry; D007700:Kinetics; D010539:Permeability; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus; D000535:Aluminum